 // 随机验证码
// 忘记密码随机验证码
    var code ;
        function createCode(){  
            code = "";   
            var codeLength = 4;//验证码的长度  
            var checkCode = document.getElementById("code3");     
            var random = new Array(0,1,2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R',  
                 'S','T','U','V','W','X','Y','Z');//随机数  
         for(var i = 0; i < codeLength; i++) {//循环操作  
            var index = Math.floor(Math.random()*36);//取得随机数的索引（0~35）  
                code += random[index];//根据索引取得随机数加到code上  
    }  
    checkCode.value = code;//把code值赋给验证码  
}  